The RMT union has called for last-ditch talks with Southern Railway to try to avert a three-day strike this week.

Members of the Rail, Maritime and Transport (RMT) union will take action from Tuesday in the long-running dispute over the role of conductors.

Customers have already suffered months of delayed and cancelled trains due to the row, while several demonstrations have been held at Victoria Station.

Talks aimed at breaking the deadlock collapsed on Thursday but the union has suggested making one more attempt to reach a deal, at the conciliation service Acas on Monday.

The union has advised its members to sign new contracts agreeing to the role of on-board supervisor.

Southern Rail: How the dispute began

However, Southern said that Acas is “no longer an option”, having been there “countless times without success”.

A spokesman said: "RMT had a chance last Thursday to shake hands on a deal with us and rejected it, only to then tell their members to accept the new role 24 hours later."

Govia Thameslink Railway (GTR), which owns Southern, also criticised the union for pressing ahead with the strikes.

Chief executive Charles Horton said: "They reject an offer one day, tell conductors to sign up to the role the next, but then still issue a clarion call to strike about it a few days later.

"To go ahead with these strikes just days after telling conductors to accept our offer sets new standards in union militancy.

Commuters protest at Victoria station in response to ongoing Southern Rail problems

"They don't care that hundreds of thousands of commuters will face yet more travel misery this week. It's clear this is all about the union trying to hang on to power and control.

"I urge them to call off what is a pointless and unnecessary dispute, as it always has been."

RMT general secretary Mick Cash said: "Despite the company spin today there is no climbdown from the union. Our dispute remains on and the fight for safety continues despite the bullying and threats from Southern.

"We have a duty to issue our members with clear legal advice that protects their position in the teeth of the threat of mass sackings. That is what we have done.

"The union offered to bring Acas in at the talks at the back end of last week in an effort to close the gap between the two sides and to reach a negotiated settlement.

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"GTR turned that down flat but the offer still stands. The union is geared up and ready for those talks on Monday."

Southern said it will extend the service it has offered on previous strike days during this week's walkout.

Nearly all 156 stations will have either a train or bus service of some description on the strike days and many routes will have trains running later in the day than on previous occasions.

Southern expects to run 80 more trains than before and 61% of its normal full timetable.

There will be extra staff at stations to help passengers and arrangements will be in place for passengers to use alternative transport providers.

Southern said: "There will still be a restricted service, with many routes having fewer trains, and unfortunately on some routes there will be no train service at all but here there will be buses in the peak.

"On some routes, a service will be provided through ticket acceptance with other train operators. Passengers are urged to plan ahead."